fix(bazel): ng-new should run yarn install (#28381)

yarn install was disabled in ng-new for Bazel schematics because
Bazel manages its own node_modules dependencies and therefore
there is no need to install dependencies twice.

However, the first yarn install is needed for `ng` commands to work,
most notably `ng build`.

This commit restores the original behavior.

PR Close #28381

integration/bazel-schematics/test.sh

@@ -10,7 +10,6 @@ function testBazel() {
   ng new demo --collection=@angular/bazel --defaults --skip-git
   node replace_angular_repo.js "./demo/WORKSPACE"
   cd demo
-  yarn install
   cp ../package.json.replace ./package.json
   ng build
   ng test